1. Field of the Invention
The present invention relates to a facility for an oil well and more particularly, but not exclusively, to a facility for an activated oil well, in which well the flow of the hydrocarbons from the bottom to the surface is assisted, temporarily or continuously by a means of activation, for example a pump whose delivery is placed at the bottom of the well.
2. Description of Related Art
In some oil wells the natural flow of the hydrocarbons from the bottom to the surface is found to be insufficient to permit or maintain commercial production. This is due either to the high viscosity of the hydrocarbons or to a very low natural pressure at the bottom of the well or else to a combination of both. To make it possible to bring the well into production on a commercial scale it is possible to employ an assistance system or a well activation system. For example, it is possible to place a pump at the lower end of a production tubing situated in the well. This pump, provided with an electrical motor immersed at the bottom of the well and powered by a cable placed in the annular space between the casing and the well casing, conveys hydrocarbons under pressure from the bottom to the surface. The power cable of the electrical motor, as well as the connections at each of its ends, run in an attacking, and frequently hot and corrosive medium, and are subjected to large variations in gas pressure and thus are subject to rapid deterioration. The replacement of this electrical equipment is a costly operation which additionally involves production losses during the stoppage in well operation.
The use of an electrical motor at the bottom of a well presents other disadvantages where the power cable is concerned because it requires high-grade leakproofing at the point where the cable enters a part of the well in contact with the effluents emanating from the oil-bearing rock, or passes through the wellhead unit placed at the surface. This leakproofing, which is difficult to achieve, is often the cause of short circuits which damage the plant and make it inoperative.
In addition, in a facility of this type, in which a single casing is installed, the operation is often handicapped by the presence of gas which it may be necessary to separate from the liquids and to convey via the annular space.